Conventionally, a projector that makes an optical modulator to modulate a light beam irradiated by a light source in accordance with image information and form an optical image and projects the optical image in an enlarged manner has been known (for example, refer to Patent Publication 1 (JP2002-31843A)).
The projector includes an optical device that mainly consists of: optical components such as a lens for superposing the light beam irradiated by the light source on an image formation area of the optical modulator, a dichroic mirror for separating the light beam irradiated by the light source into three color lights (R, G and B) and a reflection mirror for conducting the light beam irradiated by the light source to the optical modulator; and an optical component casing, in which the optical components are housed and arranged at predetermined positions on an illumination optical axis of the light beam irradiated by the light source.
The optical component casing is a synthetic resin molding product which is manufactured by molding such as injection molding with grooves formed on an inner side thereof to respectively engage with the optical components.
Such optical device is so manufactured that the respective optical components are slid from an upper side of the optical component casing to be housed and arranged therein to engage with the grooves of the optical component casing. In other words, the grooves formed on the inner side of the optical component casing serve as external position reference of the optical component casing.
However, in the above-described manufacturing method of the optical device, though the optical component can easily be housed and arranged in the optical component casing, the groove formed on the inner side of the optical component casing requires to be formed in a highly accurate manner. Thus, since a molding die for the optical component casing needs to be a complicated profile and to be highly accurately manufactured, the production cost of the optical component casing may be increased, and consequently, the production cost of the optical device may be increased.
An object of the present invention is to provide a manufacturing method of an optical device that can reduce the production cost and can easily be manufactured.